Background: Giant parathyroid adenoma presenting with a brown tumor is considered extremely rare.
Case Presentation: A 21-year-old woman presented to the clinic with persistent pain in her right knee. A radiographic examination showed an osteolytic lesion in her right tibia. Blood laboratory tests revealed that serum calcium and intact parathyroid hormone were increased significantly. Physical examination showed a 3-cm, firm, immovable lump in her neck. Ultrasonography of the patient’s neck revealed a 3.5-cm, well-circumscribed mass with a homogeneous internal texture. Computed tomography also showed a localized tumor with clear margins. The 99mTc-MIBI scintigraphy showed a hot spot in the right inferior gland. Based on these findings we judged that she had giant parathyroid adenoma presenting with a brown tumor. We ruled out the possibility of carcinoma based on image studies. We performed a parathyroidectomy via a small incision. The excised parathyroid gland weighed 10.3 g. The patient’s postoperative course was unremarkable.
Conclusions: Giant parathyroid adenoma presenting with a brown tumor is extremely rare. Accordingly, the differentiation between giant adenoma and parathyroid carcinoma is crucial. However, we could rule out the possibility of carcinoma based on imaging studies, including ultrasonography and computed tomography. As a result, we performed successful parathyroidectomy with a small incision.